The present invention relates to a flame retardant resin composition for use in wire and cable covering material. More specifically, the present invention relates to a flame retardant resin composition for use in wire and cable covering material that has excellent flame retardancy using non-halogenated materials, especially in the absence of explosion at the time of combustion or dripping of the resin, and has excellent processability, heat resistance, impact strength, and flexibility.
Polyphenylene ether has excellent mechanical properties, electrical properties, heat resistance, and low temperature properties, as well as low moisture absorbance and excellent dimensional stability. However, it is deficient in molding processability and impact strength, and these problems are solved by blending it with polystyrene or high impact polystyrene to produce compositions that are widely used, for example, in electric and electronic parts, office device housings, automobile parts, precision parts, various industrial parts, etc. The classic polyphenylene ether resin composition formed from polyphenylene ether and high impact polystyrene (see U.S. Pat. No. 3,383,435) has improved impact strength, however its chemical resistance is deteriorated.
Due to this, improvement of solvent resistance and impact strength based on blending polyphenylene ether and polyolefin has been proposed in U.S. Pat. No. 3,361,851. U.S. Pat. No. 3,994,856 describes improvement of impact strength and solvent resistance based on blending a hydrogenated block copolymer of polyphenylene ether or polyphenylene ether as well as styrene group resin.
In the past, poly(vinyl chloride) resin has been widely used in resin compositions employed as a covering material of wire and cable. The poly(vinyl chloride) resin has anti thermal temperature low at 60° C. and it is also flame retardant. However, since it contains halogen, there is a fear of causing environmental pollution by generation of dioxin, etc. at the time of combustion, and regulations regarding its use have recently become stringent.
Furthermore, there are cases of using tetrafluoroethylene in resin compositions used as a covering material of wire and cables. Tetrafluoroethylene is flame retardant and has the advantage of having drip controlling properties, however, it has the disadvantages of being difficult to mix with other resin compositions and having reduced processability. Also, because of its thermal contractibility (shrinkage), it cannot be used in the 5V test of UL 94 and may be associated with electricity leakage caused by damage of the wire and cable covering material at the time of burning.
In addition to this, tetrafluoroethylene has the problem of causing environmental pollution similar to poly(vinyl chloride) resin mentioned above, since it contains fluorine.